<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
  <input v-model="h" placeholder="身高">
  <input v-model="w" placeholder="体重">
  <input type="button" value="bmi" @click="f()">
  <h2>{{info}}</h2>
</div>

<script src="https://cdn.bootcdn.net/ajax/libs/axios/0.21.1/axios.min.js"></script>
   <script src=" https://cdn.staticfile.org/vue/2.2.2/vue.min.js"></script>
     <script>
       let v=new Vue({
         el:"body>div",
         data:{
           h:"",
           w:"",
           info:""
         },
         methods:{
           f(){
               axios.get("/bmi?h="+v.h+"&w="+v.w).then(function (response) {
               v.info=response.data;
             })
           }
         }
       })

     </script>
</body>
</html>